Connectivity Provisioning Negotiation Protocol
(CPNP)OrangeRennes35000Francemohamed.boucadair@orange.comOrangeRennes35000Francechristian.jacquenet@orange.comHuawei Technologieszhangdacheng@huawei.comCentre for Research and Innovation
Hellas78, Filikis Etairias str.VolosHellas38334Greece+302421306070pgeorgat@iti.grSDN, Order Request Handling, Automation, Dynamic Provisioning,
CDN,This document specifies the Connectivity Provisioning Negotiation
Protocol (CPNP) which is used for dynamic negotiation of service
parameters.CPNP is a generic protocol that can be used for various negotiation
purposes that include (but are not necessarily limited to) connectivity
provisioning services, storage facilities, Content Delivery Networks
footprint, etc. The protocol can be extended with new Information
Elements.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.This document defines the Connectivity Provisioning Negotiation
Protocol (CPNP) that is meant to dynamically exchange and negotiate
connectivity provisioning parameters, and other service-specific
parameters, between a Customer and a Provider. CPNP is a tool that
introduces automation in the service negotiation and activation
procedures, thus fostering the overall service provisioning process.
CPNP can be seen as a component of the dynamic negotiation meta-domain
described in Section 3.4 of .CPNP is a generic protocol that can be used for other negotiation
purposes than connectivity provisioning. For example, CPNP can be used
to request extra storage resources, to extend the footprint of a CDN
(Content Delivery Networks), to enable additional features from a cloud
Provider, etc. CPNP can be extended with new Information Elements
(IEs). describes a Connectivity Provisioning
Profile (CPP) template to capture connectivity requirements to be met by
a transport infrastructure for the delivery of various services such as
Voice over IP (VoIP), IPTV, and Virtual Private Network (VPN) services
. The CPP document defines the set of IP
transfer parameters that reflect the guarantees that can be provided by
the underlying transport network together with reachability scope and
capacity needs. CPNP uses the CPP template to encode connectivity
provisioning clauses.As a reminder, several proposals have been made in the past by the
(research) community (e.g., COPS-SLS, Service Negotiation Protocol
(SrNP), Dynamic Service Negotiation Protocol (DSNP), Resource
Negotiation and Pricing Protocol (RNAP), Service Negotiation and
Acquisition Protocol (SNAP), etc.). It is out of the scope of this
document to elaborate on the differences between CPNP and the
aforementioned proposals.This document is organized as follows: defines the functional elements
involved in CPNP exchanges. introduces several order processing
models and precises those that are targeted by CPNP. enumerates a non-exhaustive list of
use cases that could benefit from CPNP. discusses CPNP deployment models. presents the CPNP negotiation
model. provides an overview of the
protocol. specifies the CPNP objects. describes the CPNP message
validation procedure. specifies the behavior of the
involved CPNP functional elements. discusses relevant operational
guidelines. discusses protocol security
aspects.This document makes use of the following terms:Is a business role which denotes an entity
that is involved in the definition and the possible negotiation of a
contract, including a Connectivity Provisioning Agreement, with a
Provider. A connectivity provisioning contract is captured in a
dedicated CPP template-based document, which specifies (among other
information): the sites to be connected, border nodes, outsourced
operations (e.g., routing, force via points). The right to invoke the subscribed service may be
delegated by the Customer to third-party End Users, or brokering
services.A Customer can be a Service
Provider, an application owner, an enterprise, a user, etc.Owns and administers
one or many transport domain(s) (typically Autonomous System (AS))
composed of IP switching and transmission resources (e.g., routing,
switching, forwarding, etc.). Network Providers are responsible for
ensuring connectivity services (e.g., offering global or restricted
reachability at specific rates). Offered connectivity services may
not necessarily be restricted to IP. The
policies to be enforced by the connectivity service delivery
components can be derived from the technology-specific clauses that
might be included in contracts agreed with the Customers. If no such
clauses are included in the agreement, the mapping between the
connectivity requirements and the underlying technology-specific
policies to be enforced is deployment-specific.Denotes a request made by the
Customer to the Provider that includes a set of requirements. The
Customer may express its service-specific requirements by assigning
(fixed or loosely defined) values to the information items included
in the commonly understood template (e.g., CPP template) describing
the offered service. These requirements constitute the parameters to
be mutually agreed upon.Refers to a response made by the Provider to a
Customer 's quotation order as to the extent at which the Provider
may satisfy the order at the time of its receipt. Offers reflect the
capability of the Provider in accommodating received Customer orders
beyond monolithic ‘yes/no’ answers. An offer may fully or partially meet the
requirements of the corresponding order. In the latter case, it may
include alternative suggestions which the Customer may take into
account by issuing a new order.Refers to an order placed by the Customer
and accepted by the Provider. It signals the successful conclusion
of a negotiation cycle.The following functional elements are defined:Denotes a software instance
that sends CPNP requests and receives CPNP responses. The current
operations that can be performed by a CPNP client are listed
below:Create a quotation order ().Cancel an ongoing quotation order under negotiation ().Accept an offer made by a server ().Withdraw an agreement ().Update an agreement ().Denotes a software instance
that receives CPNP requests and sends back CPNP responses
accordingly. The CPNP server is responsible for the following
operations:Process a quotation order ().Make an offer ().Cancel an ongoing quotation order ().Process an order withdrawal ().For preparing their service orders, the Customers may need to be
aware of the offered services. The Providers therefore should first
proceed with the announcement of the services that they can provide. The
service announcement process may take place at designated global or
Provider-specific service markets, or through explicit interactions with
the Providers. The details of this process are outside the scope of a
negotiation protocol.With or without such service announcement mechanisms in place, the
following order processing models can be distinguished:The following order processing models can be distinguished:The Customer cannot actually negotiate
the parameters of the service(s) offered by a Provider. After
consulting the Provider's service portfolio, the Customer selects
the service offer he/she wants to subscribe and places an order to
the Provider. Order handling is quite simple on the Provider side
because the service is not customized as per Customer's
requirements, but rather pre-designed to target a group of customers
having similar requirements (i.e., these customers share the same
Customer Provisioning Profile).Unlike the frozen model, the
Customer documents his/her requirements in a request for a
quotation, which is then sent to one or several Providers. Solicited
Providers check whether they can address these requirements or not,
and get back to the Customer accordingly, possibly with an offer
that may not exactly match customer's requirements (e.g., a 100 Mbps
connection cannot be provisioned given the amount of available
resources, but an 80 Mbps connection can be provided). A negotiation
between the Customer and the Provider(s) then follows to the end of
reaching an agreement.Both frozen and negotiation-based models require the existence of
appropriate service templates like a CPP template and their
instantiation for expressing specific offerings from Providers and
service requirements from Customers, respectively. CPNP can be used in
either model for automating the required Customer-Provider interactions.
Since the frozen model can be seen as a special case of the
negotiation-based model, not only ‘yes/no’ answers but also
counter offers may be issued by the Provider in response to Customer
orders, this document focuses on the negotiation-based model.Order processing management on the Network Provider's side is usually
connected with the following functional blocks: Network Provisioning (including Order Activation, Network
Planning, etc.)Authentication, Authorization and Accounting (AAA)Network and service management (performance verification,
complaint analysis, etc.)Sales-related functional blocks (e.g., billing, invoice
validation, etc.)Network Impact AnalysisCPNP does not assume any specific knowledge about these functional
blocks, drawing an explicit line between protocol operation and the
logic for handling connectivity provisioning requests. Evidently order
handling logic is subject to the information manipulated by these
blocks. For example, the resources that can be allocated to accommodate
Customer's requirements may depend on network availability estimates as
calculated by the planning functions and related policies as well as on
the number of orders to be processed simultaneously over a given period
of time.This document does not elaborate on how Customers are identified and
subsequently managed by the Provider's Information System.A non-exhaustive list of CPNP use cases is provided below: introduces the L3VPN Service Order
Management functional block which is responsible for managing the
requests initiated by the Customers and tracks the status of the
completion of the related operations. CPNP can be used between the
Customer and the Provider to negotiate L3VPN service parameters.
A CPNP server could therefore be part of
the L3VPN Service Order Management functional block discussed in
. A YANG data model for L3VPN service
delivery is defined in .CPNP can be used between two adjacent domains to deliver IP
interconnection services (e.g., enable, update, disconnect). For
example, two Autonomous Systems (ASes) can be connected via several
interconnection points. CPNP can be used between these ASes to
upgrade existing links, request additional resources, provision a
new interconnection point, etc. See, for
example, the framework documented in .An integrated Provider can use CPNP to rationalize connectivity
provisioning needs related to its service portfolio. A CPNP server
function is used by network operations teams. A CPNP interface to
invoke CPNP negotiation cycles is exposed to service management
teams.Service Providers can use CPNP to initiate connectivity
provisioning requests towards a number of Network Providers so that
to optimize the cost of delivering their services. Although multiple
CPNP ordering cycles can be initiated by a Service Provider towards
multiple Network Providers, a subset of these orders may actually be
put into effect.For example, a cloud
Service Provider can use CPNP to request more resources from Network
Providers.CPNP can also be used in the context of network slicing () to request for
network resources together with a set of requirements that need to
be satisfied by the Provider. Such requirements are not restricted
to basic IP forwarding capabilities, but may also include a
characterization of a set of service functions that may be
invoked.CPNP can be used in Machine-to-Machine (M2M) environments to
dynamically subscribe to M2M services (e.g., access to data
retrieved by a set of sensors, extend sensor coverage, etc.).Also, Internet of Things (IoT, ) domains may rely on CPNP to enable dynamic
provisioning of data produced by involved objects, according to
their specific policies, to various external stakeholders such as
data analytics and business intelligence companies. Direct
CPNP-based interactions between IoT domains and interested parties
enable open access to diverse sets of data across the Internet,
e.g., from multiple types of sensors, user groups and/or
geographical areas.CPNP can be used in the context of I2NSF () to capture the
customer-driven policies to be enforced by a set of Network Security
Functions.A Provider offering cloud services can expose a CPNP interface to
allow Customers to dynamically negotiate related service features
such as additional storage, processing and networking resources,
enhanced security filters, etc.In the inter-cloud context (also called cloud of clouds or cloud
federation), CPNP can be used to reserve external computing and
networking resources in other cloud environments.CDN Providers can use CPNP to extend their footprint by
interconnecting their CDN infrastructure (see ).Mapping Service Providers (MSPs, )
can use CPNP to enrich their mapping database by interconnecting
their mapping system (see ). This
interconnection allows to relax the constraints on PxTR in favour of
native LISP forwarding . Also, it
allows to prevent fragmented LISP mapping database. A framework is
described in .Several CPNP deployment models can be envisaged. Two examples are
listed below:The Customer deploys a CPNP client while one or several CPNP
servers are deployed by the Provider.The Customer does not enable any CPNP client. The Provider
maintains a Customer Order Management portal. The Customer can
initiate connectivity provisioning quotation orders via the portal;
appropriate CPNP messages are then generated and sent to the
relevant CPNP server. In this model, both the CPNP client and CPNP
server are under the responsibility of the same administrative
entity (i.e., Network Provider).Once the negotiation of connectivity provisioning parameters is
successfully concluded that is, an order has been placed by the
Customer, the actual network provisioning operations are initiated. The
specification of related dynamic resource allocation and policy
enforcement schemes, as well as how CPNP servers interact with the
network provisioning functional blocks at Provider sides are out of the
scope of this document.This document does not make any assumption about the CPNP deployment
model either.CPNP runs between a Customer and a Provider carrying service orders
from the Customer and respective responses from the Provider to the end
of reaching a connectivity service provisioning agreement. As the
services offered by the Provider are well-described, by means of the CPP
template, the negotiation process is essentially a value-settlement
process, where an agreement is pursued on the values of the commonly
understood information items (service parameters) included in the
service description template.The protocol is transparent to the content that it carries and to the
negotiation logic, at Customer and Provider sides, that manipulates the
content.The protocol aims at facilitating the execution of the negotiation
logic by providing the required generic communication primitives.Since negotiations are initiated and primarily driven by the
Customer's negotiation logic, it is reasonable to assume that the
Customer can only call for an agreement. An implicit approach is adopted
for not overloading the protocol with additional messages. In
particular, the acceptance of an offer made by the Provider signals a
call for agreement from the Customer. Note that it is almost certain the
Provider to accept this call since it refers to an offer that itself
made. Of course, at any point the Provider or the Customer may quit the
negotiations, each on its own grounds.Based on the above, CPNP adopts a Quotation Order/Offer/Answer model,
which proceeds through the following basic steps:The client specifies its service requirements via a Provision
Quotation Order (PQO). The order may include fixed or loosely
defined values in the clauses describing service provisioning
characteristics.The server declines the PQO, or makes an offer to address the
requirements of the PQO, or which may suggests a counter-proposals
that partially addresses the requirements of the PQO for specific
requirements that cannot be accommodated.The client either accepts or declines the offer. Accepting the
offer implies a call for agreement.Multiple instances of CPNP may run at Customer or Provider domains. A
CPNP client may be engaged simultaneously in multiple negotiations with
the same or different CPNP servers (parallel negotiations, see ) and a CPNP server may need to negotiate with
other Provider(s) as part of negotiations with a CPNP client (cascaded
negotiations, see ).CPNP relies on various timers to achieve its operations. These timers
are used to guide the negotiation logic at both CPNP client and CPNP
server sides, particularly in cases where the CPNP client is involved in
parallel negotiations with several CPNP servers or in cases where the
CPNP server is, in its turn, involved in negotiations with other
Providers for processing a given quotation order. Related to the above,
CPNP allows the CPNP server to request for more time. This request may
be accepted or rejected by the CPNP client.Providers may need to publish available services to the Customers
(see ). CPNP may optionally support this
functionality. Dedicated templates can be defined for the purpose of
service announcements, which will be used by the CPNP clients to
initiate their CPNP negotiation cycles.For simplicity, a single Offer/Answer stage is assumed within one a
CPNP negotiation cycle. Nevertheless, as stated before, multiple CPNP
negotiation cycles can be undertaken by a CPNP client (see ).The model is flexible as it can accommodate changing conditions over
time (e.g., introduction of an additional VPN site).| |=====Quotation Order=====>|
|<==========Offer==========| |<==========Offer==========|
|===========Accept========>| |==========Decline========>|
1-Step Successful Negotiation 1-Step Failed Negotiation
Cycle Cycle
+------+ +------+ +------+ +------+
|Client| |Server| |Client| |Server|
+------+ +------+ +------+ +------+
|===Quotation Order(a)====>| |===Quotation Order(i)====>|
|<==========Offer==========| |<==========Offer==========|
|==========Decline========>| |==========Decline========>|
|===Quotation Order(b)====>| |===Quotation Order(j)====>|
|<==========Offer==========| |<==========Offer==========|
|===========Accept========>| |==========Decline========>|
|===Quotation Order(k)====>|
|<==========Offer==========|
|==========Decline========>|
|===Quotation Order(l)====>|
|<==Fail to make an offer==|
N-Step Negotiation Cycle: N-Step Negotiation Cycle:
Successful Negotiation Failed Negotiation
]]>CPNP is a client/server protocol which is designed to run over any
transport protocol with UDP being the default transport mode. No
permanent CPNP session needs to be maintained between the client and
the server. There is no need to run CPNP over a reliable transport
mode because CPNP messages are acknowledged.The server advertises the port (CPNP_PORT) it uses to bind the CPNP
service (e.g., using SRV ). The client
sends CPNP messages to CPNP_PORT; this port is discovered as per . The same port used as the source port of the
request sent to the server MUST be used by the server to reply to that
request.CPNP is independent of the IP address family.CPNP retransmission is discussed in .The CPNP client can be configured with the CPNP server(s)
(typically, an IP address together with a port number) using manual or
dynamic configuration means. For example, Providers may configure
dedicated SRV records or may use a well-known name/address.Discussions about how the client can discovers its the server(s) of
its interest are out of the scope of this document. The document
assumes that a the required CPNP server can be reached by the CPNP
client, thanks to some configuration means.As an input to its decision-making process, the CPNP server may be
connected to various external modules such as: Customer Profiles,
Network Topology, Network Resource Management, Orders Repository, AAA
and Network Provisioning Manager (an example is shown in ).These external modules provide inputs to the CPNP server, so that
it can:Check whether a customer is entitled to initiate a provisioning
quotation request.Check whether a customer is entitled to cancel an on-going
order.Check whether administrative data (e.g., billing-related
information) have been verified before starting handling the
request.Check whether network capacity is available or additional
capacity is required.Receive guidelines from network design and sales blocks (e.g.,
pricing, network usage levels, threshold on number of CPP
templates that can be processed over a given period of time as a
function of the nature of the service to be delivered, etc.).Transfer completed orders to network provisioning blocks.The above list of CPNP server operations is not
exhaustive.The following order handling modes can be also configured on the
server:Fully automated mode: This mode does not require any action
from the administrator when receiving a request for a service. The
server can execute its decision-making process related to the
orders received and generate corresponding offers.Administrative validation checking: Some or all of the server's
operations are subject to administrative validation procedures.
This mode requires an action from the administrator for every
request received. The CPNP methods which can be automatically
handled by the server or they are subject to one or several
validation administrative checks can be configured on the
server.Both the client and server maintain the following CPNP transport
session information:A CPNP session is identified by the following items:IP address of the clientClient's port numberIP address of the serverServer's port numberAn extended PQO session is denoted by a 5-uplet defined as
follows:CPNP session ()Incremented Sequence Number ()Customer Agreement Identifier: This is a unique identifier
assigned to the order under negotiation by the client (). This identifier is also used to identify
the agreement that will result from a successful negotiation.Provider Agreement Identifier: This is a unique identifier
assigned to the order under negotiation by the server (). This identifier is also used to identify
the agreement that will result from a successful negotiation.Transaction-ID ()A CPNP transaction occurs between a client and a server for
pursuing, modifying, withdrawing a service agreement and comprises all
CPNP messages exchanged between the client and the server, from the
first request sent by the client to the final response sent by the
server. A CPNP transaction is bound to a CPNP session.Because multiple CPNP transactions can be maintained by the CPNP
client, the client must assign an identifier to uniquely identify a
given transaction. This identifier is denoted as Transaction-ID.The Transaction-ID must be randomly assigned by the CPNP client,
according to the best current practice for generating random numbers
that cannot be guessed easily.
Transaction-ID is used for validating CPNP responses received by the
client.In the context of a transaction, the client needs to randomly
select a sequence number and assign it in the first CPNP message to
send. This number is then incremented for each request message is
subsequently sent within the on-going CPNP transaction (see ).CPNP adopts a simple retransmission procedure which relies on a
retransmission timer denoted as RETRANS_TIMER and maximum retry
threshold. The use of RETRANS_TIMER and a maximum retry threshold are
described in .The response timer (RESPONSE_TIMER) is set by the client to denote
the time, in seconds, the client will wait for receiving a response
from the server to a provisioning quotation order request (see ). If the timer expires, the respective
quotation order is cancelled by the client and a CANCEL message is
generated accordingly.An offer expiration timer (EXPIRE_TIMER) is set by the server to
represent the time, in minutes, after which an offer made by the
server will be invalid (see ).The current CPNP operations are listed below. They may be
augmented, depending on the nature of some transactions or because of
security considerations that may necessitate a distinct CPNP
client/server authentication phase before negotiation begins.QUOTATION (): This operation is used by the client to initiate
a provisioning quotation order. Upon receipt of a QUOTATION
request, the server may respond with a PROCESSING, OFFER or a FAIL
message. A QUOTATION-initiated transaction can be terminated by a
FAIL message.PROCESSING (): This operation is used to inform the remote party
that the message (the order quotation or the offer) sent was
received and it is processed. This message can also be issued by
the server to request more time, in which case the client may
reply with an ACK or FAIL message depending on whether more time
can or cannot be granted.OFFER (): This operation is used by the server to inform
the client about an offer that can best accommodate the
requirements indicated in the previously received QUOTATION
message.ACCEPT (): This operation is used by the client to confirm
the acceptance of an offer made by the server. This message
implies a call for agreement. An agreement is reached when an ACK
is subsequently received from the server, which is likely to
happen; it is rather unlikely the server to reject an offer that
it has already made.DECLINE (): This operation is used by the client to reject an
offer made by the server. The on-going transaction may not be
terminated immediately, e.g., the server/client may issue another
offer/order.ACK (): This
operation is used by the server to acknowledge the receipt of an
ACCEPT or WITHDRAW message, or by the client to confirm the time
extension requested by the server for processing the last received
quotation order.CANCEL (): This operation is used by the client to cancel
(quit) the on-going transaction.WITHDRAW (): This operation is used by the client to withdraw
an agreement.UPDATE (): This operation is used by the client to update an
existing agreement. For example, this method can be invoked to add
a new site. This method will trigger a new negotiation cycle.FAIL (): This operation is used by the server to indicate
that it cannot accommodate the requirements documented in the PQO
conveyed in the QUOTATION message or to inform the client about an
error encountered when processing the received message. In either
case, the message implies that the server is unable to make offers
and as such it terminates the on-going transaction. This message is also used by the client to reject
a time extension request received from the server (in a PROCESSING
message). The message includes a status code for providing
explanatory information.The above CPNP primitives are service-independent. CPNP messages
may transparently carry service-specific objects which are handled by
the negotiation logic at either side.The document specifies the service objects that are required for
connectivity provisioning negotiation (see ). Additional service-specific objects to be
carried in the CPNP messages can be defined in the future for
accommodating alternative deployment or other service provisioning
needs.CPNP makes use of several flavors of Connectivity Provisioning
Documents (CPD). These documents follow the CPP template described in
.Refers
to the CPD included by a CPNP client in a QUOTATION request.This
document is included by a CPNP server in an OFFER message. Its
information reflects the proposal of the server to accommodate all
or a subset of the clauses depicted in a Requested CPD. A validity
time is associated with the offer made.If
the client accepts an offer made by the server, the Offered CPD is
included in an ACCEPT message. This CPD is also included in an ACK
message. Thus, a 3-way hand-shaking procedure is followed for
successfully concluding the negotiation. shows a typical CPNP negotiation
cycle and the use of the different types of Connectivity Provisioning
Documents.|
|<============PROCESSING==============|
|<========OFFER (Offered CPD)=========|
|=============PROCESSING=============>|
|=========ACCEPT (Agreed CPD)========>|
|<=========ACK (Agreed CPD)===========|
| |
]]>A provisioning document can include parameters with fixed values,
loosely defined values, or a combination thereof. A provisioning
document is said to be concrete if all clauses have fixed values.A typical evolution of a negotiation cycle would start with a
quotation order with loosely defined parameters, and then, as offers
are made, it would conclude with concrete provisioning document for
calling for the agreement.If the server detects that network resources from another Network
Provider need to be allocated in order to accommodate the requirements
described in a PQO (e.g., in the context of an inter-domain VPN
service, additional PE router resources need to be allocated), the
server may generate child PQOs to request the appropriate network
provisioning operations (see ). In such
situation, the server behaves also as a CPNP client. The server
associates the parent order with its child PQOs. This is typically
achieved by locally adding the reference of the child PQO to the
parent order.| |
|<====PROCESSING=====| |
| |=====QUOTATION=====>|
| |<====PROCESSING=====|
| |<=======OFFER=======|
| |=====PROCESSING====>|
| |=======ACCEPT======>|
| |<=======ACK=========|
|<=======OFFER=======| |
|=====PROCESSING====>| |
|=======ACCEPT======>| |
|<=======ACK=========| |
| | |
]]>A CPNP client may undertake multiple negotiations in parallel with
several servers for practical reasons such as cost optimization and
fail-safety. The multiple negotiations may lead to one or many
agreements. Multiple negotiations with the same Provider are not
precluded.The salient point underlining the parallel negotiations scenario is
that although the negotiation protocol is strictly between two
parties, the negotiation logic may not necessarily be. The CPNP client
negotiation logic may need to collectively drive parallel
negotiations, as the negotiation with one server may affect the
negotiation with other servers; e.g., it may need to use the responses
from all servers as input for determining the messages (and their
content) to subsequently send in each individual negotiation. Timing
is therefore an important aspect at the client's. The CPNP client
needs to have the ability to synchronize the receipt of the responses
from the servers. CPNP takes into account this requirement by allowing
clients to specify in the QUOTATION message the time by which the
server needs to respond (see ).Both the client and the server maintain repositories to store
on-going orders. How these repositories are maintained is
deployment-specific. It is out of scope of this document to elaborate
on such considerations. Timestamps are also logged to track state
change. Tracking may be needed for various reasons,including
regulatory ones.The following lists the states which can be associated with a
given order on the client's side:Created: when the order has been created. It is not handled
by the client until the administrator allows to process it.AwaitingProcessing: when the administrator approved of
processing a created order and the order has not been handled
yet.PQOSent: when the order has been sent to the server.ServerProcessing: when the server has confirmed the receipt
of the order.OfferReceived: when an offer has been received from the
server.OfferProcessing: when a received offer is currently processed
by the client.AcceptSent: when the client confirmed the offer to the
server.AcceptAck: when the offer is acknowledged by the server.Cancelled: when the order has failed or cancelled.| A |
+------------------+ FAIL | N |
| | C |
| | E |
OFFER | L |
| | L |
v | E |
+------------------+ | D |
| OfferReceived |---CANCEL--->| |
+------------------+ | |
| PROCESSING +-----+
v ^^^
+------------------+ |||
| OfferProcessing |---DECLINE-----+||
+------------------+ ||
| ACCEPT ||
v ||
+------------------+ ||
| AcceptSent |---CANCEL-------+|
+------------------+ |
| ACK |
v |
+------------------+ |
| AcceptAck |---WITHDRAW------+
+------------------+
]]>The following lists the states which can be associated with a
given order and a corresponding offer on the server's side:PQOReceived: when the order has been received from the
client.AwaitingProcessing: when the order is being processed by the
server. An action from the server administrator may be
needed.OfferProposed: when the request has been successfully handled
and an offer has been sent to the client.ProcessingReceived: when the server received a PROCESSING for
an offer sent to the client.AcceptReceived: when the server received a confirmation for
the offer from the client.AcceptAck: when the server acknowledged the offer (accepted
by client) to the client.Cancelled: when the order has failed to be met or it has been
cancelled by the client. Associate resources must be released in
the latter case, if prior reserved.ChildCreated: when a child order has been created in cases
where resources from another Network Provider are needed.ChildPQOSent: when a child order has been sent to the remote
server.ChildServerProcessing: when a child order is currently
processed by the remote server.ChildOfferReceived: when an offer has been received to a
child order from the remote server.ChildOfferProcessing: when a received offer to a child order
is currently processed.ChildAcceptSent: when the child offer (offer received from
the remote server in response to a child order) is confirmed to
the remote server.ChildAcceptAck: when an accepted child offer is acknowledged
by the remote server.This section defines CPNP objects using the RBNF format defined at
.Note: The formats of CPNP messages are provided using a generic
format. Implementors can adapt RBNF definitions to their "favorite"
message format.CUSTOMER_AGREEMENT_IDENTIFIER is an identifier which is assigned
by a client to identify an agreement. This identifier must be unique
to the client.Rules for assigning this identifier are specific to the client
(Customer). The value of CUSTOMER_AGREEMENT_IDENTIFIER is included
in all CPNP messages.The client (Customer) assigns an identifier to an order under
negotiation before an agreement is reached. This identifier will be
used to unambiguously identify the resulting agreement at the client
side (Customer).The server handles CUSTOMER_AGREEMENT_IDENTIFIER as an opaque
value.PROVIDER_AGREEMENT_IDENTIFIER is an identifier which is assigned
by a server to identify an order. This identifier must be unique to
the server.Rules for assigning this identifier are specific to the server
(Provider). The value of PROVIDER_AGREEMENT_IDENTIFIER is included
in all CPNP messages, except QUOTATION messages.The server (Provider) assigns an identifier to an order under
negotiation before an agreement is reached. This identifier will be
used to unambiguously identify the resulting agreement at the server
side (Provider).The client handles PROVIDER_AGREEMENT_IDENTIFIER as an opaque
value.This object conveys the Transaction-ID introduced in .Sequence Number is a number that is monotonically incremented on
every new CPNP message within a CPNP transaction. This number is
used to avoid reply attacks.Refer to .NONCE is a random value assigned by the CPNP server. It is
RECOMMENDED to assign unique NONCE values for each order.NONCE is then mandatory to be included in subsequent CPNP client
operations on the associated order (including the resulting
agreement) such as: withdraw the order or update the order.If the NONCE validation checks fail, the server rejects the
request with a FAIL message including the appropriate failure reason
code.This attribute indicates the time by when the CPNP client is
expecting to receive a response, for a PQO, from the CPNP server. If
no offer is received by then, the CPNP client will consider the
quotation order as rejected.EXPECTED_RESPONSE_TIME follows the date format specified in .This attribute indicates the time by when the CPNP server is
expecting to make an offer to the CPNP client. If no offer is
received by then, the CPNP client will consider the order as
rejected.The CPNP server may propose an expected offer time that does not
match the expected response time indicated in the quotation order
message. The CPNP client can accept or rejects the proposed expected
time by when the CPNP server will make an offer.The CPNP server can always request extra time for its processing,
but this may be accepted or rejected by the CPNP client.EXPECTED_OFFER_TIME follows the date format specified in .This attribute indicates the time of validity of an offer made by
the CPNP server. If the offer is not accepted before this date
expires, the CPNP server will consider the CPNP client has rejected
the offer; the CPNP server will silently clear this order.VALIDITY_OFFER_TIME follows date format specified in .The RBNF format of the Connectivity Provisioning Document (CPD)
is shown in : ::=
...
::=
...
::=
::= ...
::= ]]>An Information Element (IE) is an optional object which can be
included in a CPNP message.The client may include administrative information such
as:NameContact InformationThe format of this Information Element is as follows: ::= ::= []
[ ...]
]]>The server may include administrative information in an offer
such as:NameAS Number ()Contact InformationThe format of this Information Element is as follows: ::= []
]]>The client may include some negotiation options such as:Cost: the client may include an empty or a preferred COST
attribute to request the cost from the server. The server will
provide the cost information in the response.Setup purpose: A client may request to setup a connectivity
only for testing purposes during a limited period. The order
can be extended to become permanent if the client was
satisfied during the test period. This operation is achieved
using UPDATE method.Other negotiation options may be defined in the
future.The format of this Information Element is as follows: ::= [][]
]]>This section specifies the RBNF format of CPNP operation messages.
The following operation codes are used: QUOTATION ()PROCESSING ()OFFER ()ACCEPT ()DECLINE ()ACK ()CANCEL ()WITHDRAW ()UPDATE ()FAIL ()The format of the QUOTATION message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER>[<EXPECTED_RESPONSE_TIME>]<REQUESTED_CONNECTIVITY_PROVISIONING_DOCUMENT>[<INFORMATION_ELEMENT>...]A QUOTATION message must include an order
identifier which is generated by the client. Because several orders
can be issued to several servers, the QUOTATION message must also
include a Transaction-ID.The message may include an EXPECTED_RESPONSE_TIME which indicates
by when the client is expecting to receive an offer from the server.
QUOTATION message must also include a requested connectivity
provisioning document.When the client sends the QUOTATION message to the server, the
state of the order changes to "PQOSent".The format of the PROCESSING message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER>[<EXPECTED_OFFER_TIME>]Upon receipt of a QUOTATION message, the
server proceeds with parsing rules (see ). If no error is encountered, the server
generates a PROCESSING response to the client to indicate the PQO
has been received and it is being processed. The server must
generate an order identifier which identifies the order in its local
order repository. The server MUST copy the content of
CUSTOMER_AGREEMENT_IDENTIFIER and TRANSACTION_ID fields as conveyed
in the QUOTATION message. The server may include an
EXPECTED_OFFER_TIME by when it expects to make an offer to the
client.Upon receipt of a PROCESSING message, the client verifies whether
it has issued a PQO to that server and which contains the
CUSTOMER_AGREEMENT_IDENTIFIER and TRANSACTION_ID. If no such PQO is
found, the PROCESSING message is silently ignored. If a PQO is
found, the client may check if it accepts the EXPECTED_OFFER_TIME
and then, it changes to state of the order to
"ServerProcessing".If more time is required by the server to process the quotation
order, it may send a PROCESSING message that includes a new
EXPECTED_OFFER_TIME. The client can answer with an ACK message if
more time is granted () or with a
FAIL message if the time extension is rejected ().|
|<========PROCESSING(time1)===========|
...
|<========PROCESSING(MoreTime)========|
|============ACK(TimeGranted)========>|
...
|<=========OFFER(Offered CPD)=========|
|=============PROCESSING=============>|
|==========ACCEPT(Agreed CPD)========>|
|<==========ACK(Agreed CPD)===========|
| |
]]>|
|<========PROCESSING(time1)===========|
...
|<========PROCESSING(MoreTime)========|
|===========FAIL(TimeRejected)=======>|
]]>The format of the OFFER message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><NONCE><VALIDITY_OFFER_TIME><OFFERED_CONNECTIVITY_PROVISIONING_DOCUMENT>[<INFORMATION_ELEMENT>...]The server answers with an OFFER message
to a QUOTATION request received from the client. The offer will be
considered as rejected by the client if no confirmation (ACCEPT
message sent by the client) is received by the server before the
expiration of the validity time.The format of the ACCEPT message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><NONCE><AGREED_CONNECTIVITY_PROVISIONING_DOCUMENT>[<INFORMATION_ELEMENT>...]This message is used by a client to
confirm the acceptance of an offer received from a server. The
fields of this message are copied from the received OFFER
message.The format of the DECLINE message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><NONCE>The client can issue a DECLINE
message to reject an offer. CUSTOMER_AGREEMENT_IDENTIFIER,
PROVIDER_AGREEMENT_IDENTIFIER, TRANSACTION_ID, and NONCE are used by
the server as keys to find the corresponding order. If an order
matches, the server changes the state of this order to "Cancelled"
and then returns an ACK with a copy of the requested CPD to the
requesting client.If no order is found, the server returns a FAIL message to the
requesting client.A flow example is shown in .|
|<============PROCESSING==============|
|<=========OFFER(Offered CPD)=========|
|=============PROCESSING=============>|
|===============DECLINE==============>|
|<================ACK=================|
| |
]]>The format of the ACK message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER>[<EXPECTED_RESPONSE_TIME>][<CONNECTIVITY_PROVISIONING_DOCUMENT>][<INFORMATION_ELEMENT>...]This message is issued by the server to
close a CPNP transaction or by a client to grant more negotiation
time to the server.This message is sent by the server as a response to an ACCEPT,
WITHDRAW, DECLINE, or CANCEL message. In such case, the ACK message
must include the copy of the Connectivity Provisioning Document as
stored by the server, in particular:A copy of the requested/offered CPD is included by the server
if it successfully handled a CANCEL message.A copy of the updated CPD is included by the server if it
successfully handled an UPDATE message.A copy of the offered CPD is included by the server if it
successfully handled an ACCEPT message in the context of a
QUOTATION transaction.An empty CPD is included by the server if it successfully
handled a DECLINE message.A client may issue an ACK message as a response to a more time
request (conveyed in PROCESSING) received from the server. In such
case, the ACK message must include an EXPECTED_RESPONSE_TIME that is
likely to be set to the time extension requested by the server.The format of the CANCEL message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER>[<CONNECTIVITY_PROVISIONING_DOCUMENT>]The client can issue a CANCEL
message at any stage during the CPNP negotiation process before an
agreement is reached. CUSTOMER_AGREEMENT_IDENTIFIER and
TRANSACTION_ID are used by the server as keys to find the
corresponding order. If a quotation order matches, the server
changes the state of this quotation order to "Cancelled" and then
returns an ACK with a copy of the requested CPD to the requesting
client.If no quotation order is found, the server returns a FAIL message
to the requesting client.The format of the WITHDRAW message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><NONCE>[<AGREED_CONNECTIVITY_PROVISIONING_DOCUMENT>][<INFORMATION_ELEMENT>...]This message is used to withdraw an offer
already subscribed by the Customer.
shows a typical usage of this message.|
|<============PROCESSING==============|
|<===========ACK(Empty CPD)===========|
| |
]]>The CPNP must include the same CUSTOMER_AGREEMENT_IDENTIFIER,
PROVIDER_AGREEMENT_IDENTIFIER, and NONCE as those used when creating
the order.Upon receipt of a WITHDRAW message, the server checks whether an
order matching the request is found. If an order is found, the state
of the order is changed to "Cancelled" and an ACK message including
an Empty CPD is returned to the requesting client. If no order is
found, the server returns a FAIL message to the requesting
client.The format of the UPDATE message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><NONCE><EXPECTED_RESPONSE_TIME><REQUESTED_CONNECTIVITY_PROVISIONING_DOCUMENT>[<INFORMATION_ELEMENT>...]This message is sent by the CPNP client
to update an existing connectivity provisioning agreement. The CPNP
must include the same CUSTOMER_AGREEMENT_IDENTIFIER,
PROVIDER_AGREEMENT_IDENTIFIER, and NONCE as those used when creating
the order. The CPNP client includes a new CPD which integrates the
requested modifications. A new Transaction_ID must be assigned by
the client.Upon receipt of an UPDATE message, the server checks whether an
order, having state "Completed", matches
CUSTOMER_AGREEMENT_IDENTIFIER, PROVIDER_AGREEMENT_IDENTIFIER, and
NONCE. If no order is found, the CPNP server generates a FAIL error
with the appropriate error code.If an order is found, the server checks whether it can honor
the request:A FAIL message is sent to the client if the server cannot
honor the request. The client may initiate a new PQO
negotiation cycle.An OFFER message including the updated connectivity
provisioning document is sent to the client. For example,
the server maintains an order for provisioning a VPN service
that connects sites A, B and C. If the client sends an
UPDATE message to remove site C, only sites A and B will be
included in the OFFER sent by the server to the requesting
client.A flow chart that illustrates the use of UPDATE operation is
shown in .|
|<============PROCESSING==============|
|<=========OFFER(Updated CPD)=========|
|=============PROCESSING=============>|
|==========ACCEPT(Updated CPD)=======>|
|<==========ACK(Updated CPD)==========|
| |
]]>The format of the FAIL message is shown below:<VERSION><METHOD_CODE><SEQUENCE_NUMBER><TRANSACTION_ID><CUSTOMER_AGREEMENT_IDENTIFIER><PROVIDER_AGREEMENT_IDENTIFIER><STATUS_CODE>This message is sent in the following
cases:The server can not honor an order received from the client
(i.e., received in a QUOTATION or UPDATE request).The server encounters an error when processing a CPNP request
received from the client.The client can not grant more time to a the server. This is a
response to a more time request conveyed in a PROCESSING
message.The status code indicates the error code. The following codes are
supported:The message can not be validated (see ).The request cannot be handled because
authentication is required.The request cannot be handled because
authorization failed.The request can not be handled because of
administrative policies.The request can not be honored because there is
not enough capacity.The request can not be honored because there is
no network presence.The request to extend the time negotiation is
rejected by the client.Both client and server proceed with CPNP message validation. The
following tables summarize the validation checks to be followed.OperationValidation ChecksPROCESSING{Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier} must
match an existing PQO with a state set to "PQOSent". The sequence
number carried in the packet must be larger than the sequence number
maintained by the client.OFFER{Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier} must
match an existing order with state set to "PQOSent" or {Source IP
address, source port, destination IP address, destination port,
Transaction-ID, Customer Order Identifier, Provider Order
Identifier} must match an existing order with a state set to
"ServerProcessing". The sequence number carried in the packet must
be larger than the sequence number maintained by the client.ACK (QUOTATION Transaction){Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier,
Provider Order Identifier, Offered Connectivity Provisioning Order}
must match an order with a state set to "AcceptSent". The sequence
number carried in the packet must be larger than the sequence number
maintained by the client.ACK (UPDATE Transaction){Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier,
Provider Order Identifier, Updated Connectivity Provisioning Order}
must match an order with a state set to "AcceptSent". The sequence
number carried in the packet must be larger than the sequence number
maintained by the client.ACK (WITHDRAW Transaction){Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier,
Provider Order Identifier, Empty Connectivity Provisioning Order}
must match an order with a state set to "Cancelled". The sequence
number carried in the packet must be larger than the sequence number
maintained by the client.MethodValidation ChecksQUOTATIONThe source IP address passes existing access filters (if any).
The sequence number carried in the packet must not be less than the
sequence number maintained by the server.PROCESSINGThe sequence number carried in the packet must be larger than the
sequence number maintained by the server.ACCEPT{Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier,
Provider Order Identifier, Nonce, Offered Connectivity Provisioning
Order} must match an order with state set to "OfferProposed" or
"ProcessngReceived". The sequence number carried in the packet must
be larger than the sequence number maintained by the server.DECLINE{Source IP address, source port, destination IP address,
destination port, Transaction-ID, Customer Order Identifier,
Provider Order Identifier, Nonce} must match an order with state set
to "OfferProposed" or "ProcessngReceived". The sequence number
carried in the packet must be larger than the sequence number
maintained by the server.UPDATEThe source IP address passes existing access filters (if any) and
{Customer Order Identifier, Provider Order Identifier, Nonce} must
match an existing order with state "Completed".WITHDRAWThe source IP address passes existing access filters (if any) and
{Customer Order Identifier, Provider Order Identifier, Nonce} must
match an existing order with state "Completed".Both CPNP client and server proceeds to message validation checks as
specified in .To place a provisioning quotation order, the client initiates
first a local quotation order object identified by a unique
identifier assigned by the client. The state of the quotation order
is set to "Created". The client then generates a QUOTATION request
which includes the assigned identifier, possibly an expected
response time, a Transaction-ID and a Requested Connectivity
Provisioning Document. The client may include additional Information
Elements such as Negotiation Options.The client may be configured to not enforce negotiation checks on
EXPECTED_OFFER_TIME; if so no EXPECTED_RESPONSE_TIME attribute (or
EXPECTED_RESPONSE_TIME set to infinite) should be included in the
quotation order.Once the request is sent to the server, the state of the request
is set to "PQOSent" and a timer, if a response time is included in
the quotation order, is set to the expiration time as included in
the QUOTATION request. The client also maintains a copy of the
extended transport session details used to generate the QUOTATION
request. The CPNP client must listen on the same port number that it
used to send the QUOTATION request.If no answer is received from the server before the
retransmission timer expires (i.e., RETRANS_TIMER, ), the client proceeds to retransmission
until maximum retry is reached (i.e., 3 times). The same sequence
number is used for retransmitted packets.If a FAIL message is received, the client may decide to issue
another (corrected) request towards the same server, cancel the
local order, or contact another server. The behavior of the client
depends on the error code returned by the server in the FAIL
message.If a PROCESSING message matching the CPNP transport session is
received, the client updates the CPNP session with the
PROVIDER_AGREEMENT_IDENTIFIER information. If the client does not
accept the expected offer time that may have been indicated in the
PROCESSING message, the client may decide to cancel the quotation
order. If the client accepts the EXPECTED_OFFER_TIME, it changes the
state of the order to "ServerProcessing" and sets a timer to the
value of EXPECTED_OFFER_TIME. If no offer is made before the timer
expires, the client changes the state of the order to
"Cancelled".As a response to a more time request (conveyed in a PROCESSING
message that included a new EXPECTED_OFFER_TIME), the client may
grant this extension by issuing an ACK message or reject the time
extension with a FAIL message having a status code set to "More Time
Rejected".If an OFFER message matching the extended CPNP session is
received, the client checks if a PROCESSING message having the same
PROVIDER_AGREEMENT_IDENTIFIER has been received from the server. If
a PROCESSING message was already received for the same order but the
PROVIDER_AGREEMENT_IDENTIFIER does not match the identifier included
in the OFFER message, the client ignores silently the message. If a
PROCESSING message having the same PROVIDER_AGREEMENT_IDENTIFIER was
already received and matches the CPNP transaction identifier, the
client changes the state of the order to "OfferReceived" and sets a
timer to the value of VALIDITY_OFFER_TIME indicated in the OFFER
message.If an offer is received from the server (i.e., as documented in
an OFFER message), the client may accept or reject the offer. The
client accepts the offer by generating an ACCEPT message which
confirms that the client agrees to subscribe to the offer documented
in the OFFER message; the state of the order is passed to
"AcceptSent". The transaction is terminated if an ACK message is
received from the server. If no ACK is received from the server, the
client proceeds with the re-transmission of the ACCEPT message.The client may also decide to reject the offer by sending a
DECLINE message. The state of the order is set by the client to
"Cancelled". If an offer is not acceptable by the client, the client
may decide to contact a new server or submit another order to the
same server. Guidelines to issue an updated order or terminate the
negotiation are specific to the client.A client may withdraw a completed order. This is achieved by
issuing a WITHDRAW message. This message must include Customer Order
Identifier, Provider Identifier and Nonce returned during the order
negotiation cycle specified in .If no ACK is received from the server, the client proceeds with
the re-transmission of the message.A client may update a completed order. This is achieved by
issuing an UPDATE message. This message must include Customer Order
Identifier, Provider Order Identifier and Nonce returned during the
order negotiation cycle specified in . The client must include in the UPDATE
message an updated CPD with the requested changes.Subsequent messages exchange is similar to what is documented in
.Upon receipt of a QUOTATION message from a client, the server
sets a CPNP session, stores Transaction-ID and generates a Provider
Order Identifier. Once preliminary validation checks are completed (
), the server may return a
PROCESSING message to notify the client the quotation order is
received and it is under processing; the server may include an
expected offer time to notify the client by when an offer will be
proposed. An order with state "AwaitingProcessing" is created by the
server. The server runs its decision-making process to decide which
offer it can make to honor the received order. The offer should be
made before the expected offer time expires.If the server cannot make an offer, it sends backs a FAIL message
with the appropriate error code.If the server requires more negotiation time, it must send a
PROCESSING message with a new EXPECTED_OFFER_TIME. The client may
grant this extension by issuing an ACK message or reject the time
extension with a FAIL message having a status code set to "More Time
Rejected". If the client doesn't grant more time, the server must
answer before the initial expected offer time; otherwise the client
will ignore the quotation order.If the server can honor the request or it can make an offer that
meet some of the requirements, it creates an OFFER message. The
server must indicate the Transaction-ID, Customer Order Identifier
as indicated in the QUOTATION message, and the Provider Order
Identifier generated for this order. The server must also include
Nonce and the offered Connectivity Provisioning Document. The server
includes an offer validity time as well. Once sent to the client,
the server changes the state of the order to "OfferSent" and a timer
set to the validity time is initiated.If the server determines that additional network resources from
another network provider are needed to accommodate a quotation
order, it will create child PQO(s) and will behave as a CPNP client
to negotiate child PQO(s) with possible partnering providers (see
).If no PROCESSING, ACCEPT or DECLINE message is received before
the expiry of the RETRANS_TIMER, the server re-sends the same offer
to the client. This procedure is repeated until maximum retry is
reached.If an ACCEPT message is received before the offered validity time
expires, the server proceeds with validation checks as specified in
. The state of the corresponding
order is passed to "AcceptReceived". The server sends back an ACK
message to terminate the order processing cycle.If a CANCEL/DECLINE message is received, the server proceeds with
the cancellation of the order. The state of the order is then passed
to "Cancelled".A client may withdraw a completed order by issuing a WITHDRAW
message. Upon receipt of a WITHDRAW message, the server proceeds
with the validation checks, as specified in .If the checks fail, a FAIL message is sent back to the client
with the appropriate error code.If the checks succeed, the server clears the clauses of the
Connectivity Provisioning Document, changes the state of the
order to "Cancelled", and sends back an ACK message with an
Empty Connectivity Provisioning Document.A client may update an order by issuing an UPDATE message. Upon
receipt of an UPDATE message, the server proceeds with the
validation checks as specified in .If the checks fail, a FAIL message is sent back to the client
with the appropriate error code.Subsequent messages exchange is similar to what is specified
in . The server should generate a
new Nonce value to be included in the offer made to the
client.In each transaction, sequence numbers are used to protect the
transaction against replay attacks. Each communicating partner of the
transaction maintains two sequence numbers, one for incoming packets
and one for outgoing packets. When a partner receives a message, it
will check whether the sequence number in the message is larger than
the incoming sequence number maintained locally. If not, the messages
will be discarded. If the message is proved to be legal, the value of
the incoming sequence number will be replaced by the value of the
sequence number in the message. When a partner sends out a message, it
will insert the value of outgoing sequence number into the message and
increase the outgoing sequence number maintained locally by 1.If a transaction partner sends out a message and does not receive
any expected reply before the retransmission timer expires (i.e.,
RETRANS_TIMER), a transaction partner will try to re-transit the
messages. An exception is the last message (e.g., ACK) sent from the
server in a transaction. After sending this message, the
retransmission timer will be disabled since no additional feedback is
expected.In addition, if the partner receives a re-sent last incoming
packet, the partner can also send out the answer to the incoming
packet with a limited frequency. If no answer was generated at the
moment, the partner needs to generate a PROCESSING message as the
answer.To benefit message re-transmission, a partner could also store the
last incoming packet and the associated answer. Note that the times of
re-transmission could be decided by the local policy and
re-transmission will not cause any change of sequence numbers.The CPNP server SHOULD be configurable to log various events and
associated information. Such information includes:Client's IP addressAny event change (e.g., new quotation order, offer sent, order
confirm, order cancellation, order withdraw, etc.)TimestampThe CPNP server can operate in the following modes: Fully automated mode: The CPNP server is provisioned with a set
of business guidelines and objectives that will be used as an
input to the decision-making process. The CPNP server will service
received orders that falls into these business guidelines;
otherwise requests will be escalated to an administrator that will
formally validate/invalidate an order request. The set of policies
to be configured to the CPNP server are specific to each
administrative entity managing a CPNP server.Administrative-based mode: This mode assumes some or all CPNP
server' operations are subject to a formal administrative
validation. CPNP events will trigger appropriate validation
requests that will be forwarded to the contact person(s) or
department which is responsible for validating the orders.
Administrative validation messages are relayed using another
protocol (e.g., SMTP) or a dedicated tool.Business guidelines are local to each administrative entity.
How validation requests are presented to an administrator are out of
scope of this document; each administrative entity may decide the
appropriate mechanism to enable for that purpose.Means to defend the server against denial-of-service attacks must be
enabled. For example, access control lists (ACLs) can be enforced on the
client, the server or the network in between, to allow a trusted client
to communicate with a trusted server.The client and the server should be mutually authenticated. Out of
band mechanisms can be used instead of integrating them into CPNP.The client must silently discard CPNP responses received from unknown
CPNP servers. The use of a randomly generated Transaction-ID makes it
hard to forge a response from a server with a spoofed IP address
belonging to a legitimate CPNP server. Furthermore, CPNP demands that
messages from the server must include correct identifiers of the orders.
Two order identifiers are used: one generated by the client and a second
one generated by the server.The Provider must enforce means to protect privacy-related
information included the documents (see )
exchanged using CPNP messages . In
particular, this information must not be revealed to external parties
without the consent of Customers. Providers should enforce policies to
make Customer fingerprinting difficult to achieve. For more discussion
about privacy, refer to .The NONCE and the Transaction ID attributes provide sufficient
randomness and can effectively tolerate attacks raised by off-line
adversaries, who do not have the capability of eavesdropping and
intercepting the packets transported between the client and the server.
Only authorized clients must be able to modify agreed CPNP orders. The
use of a randomly generated NONCE by the server makes it hard to modify
an agreement on behalf of a malicious third-party.The sequence numbers included in the CPNP messages can be used to
detect replay attacks and antique packets intercepted from on-going
transactions may be re-sent. However, the protocol in its current
version may be vulnerable to replay attacks where the replayed messages
are intercepted from antique transactions. Although the Transaction ID
provided by the client could protect inter-transaction replay attacks,
no protection is provided for the server to deal with this type of
attack.The protocol does not provide security mechanisms to protect the
confidentiality and integrity of the packets transported between the
client and the server. An underlying security protocol such as (e.g.,
DTLS , IPsec) could be used to protect the
integrity and confidentiality for the protocol. In this case, if it is
possible to provide an Automated Key Management (AKM) and associate each
transaction with a different key, inter- transaction replay attacks can
naturally be addressed. If the client and the server use a single key,
an additional mechanism should be provided to protect inter-transaction
replay attacks between them.The deployment option of a Customer Order Management portal operated
by a trusted third-party (see ) may facilitate
the efficient resolution of the aforementioned security concerns.This document does not request any IANA action.Thanks to Diego R. Lopez for his comments.Economics and Technologies of Inter-Carrier ServicesEU FP7 ETICS Project